Judges recuse themselves when they take no part in deciding cases that they would otherwise help decide. The Due Process clauses of the United States Constitution requires judges to recuse themselves from cases in two situations:
- Where the judge has a financial interest in the case's outcome.
- Where there is otherwise a strong possibility that the judge's decision will be biased.
In either case, it does not matter whether or not the judge is actually biased. What matters is that even if the judge is not biased, the high probability of bias still damages the integrity of the judicial system. Any party in a lawsuit may request that a judge recuse him or herself.
The Supreme Court addressed recusal in the 2009 case Caperton v. A. T. Massey Coal Co. (08-22). In that case, one party requested that a judge recuse himself because the other party's CEO spent over $3 million getting the judge elected. Even though the Supreme Court found that there was no evidence that the judge was biased, it still held that he had to recuse himself. For additional information on this case, see the LII's oral argument preview of it.